1. Field of the Invention
The present invention relates generally to air pumps and, more particularly, to an air pump, which provides dual charging modes, an air cylinder mode and a manual mode, to be optionally operated.
2. Description of the Related Art
Regular commercially available handy bicycle air pumps are commonly operated by hand. When in use, the user must repeatedly push and pull the piston so that external air can be sucked in and driven into the tire. These air pumps are simple. However, it requires much effort to reciprocate the piston. There are air-cylinder-actuated air pumps available on the market. When an air-cylinder-actuated air pump is used to pump the tire of a bicycle, the user directly attaches an air cylinder to the air inlet of the air-cylinder-actuated air pump, enabling compressed gas (carbon dioxide) to be discharged out of the attached air cylinder into the tire. The use of an air-cylinder-actuated air pump requires less effort.
According to conventional designs, most handy air pumps provide only one single operation mode, i.e., manual operation mode or air-cylinder-actuated operation mode. Although some air pumps with air-cylinder/manual dual charging mode have been disclosed, they are still not satisfactory in function. A conventional air cylinder loadable air pump directly discharges a compressed gas into the tire upon connecting the air nozzle connector of the air pump to the air nozzle of the tire after loading an air cylinder. This design of air pump is still not satisfactory in function because while the air cylinder is empty, the air pump can be operated only by hand before loading a new air cylinder instead of the empty one.